Directly reduced iron, or DRI, is also referred to as iron sponge or sponge iron. It is produced through the direct reduction of iron ore. The directly reduced iron can then be further processed by hot-briquetting or hot-compacting.
In a hot-briquetting installation the directly reduced iron is pressed in one or more roller presses embodied as briquette presses into briquettes that are then suitable for transport or storage, for example. The briquettes generally emerge from the press in the form of a strand, for which reason a separator is arranged downstream that then separates the briquettes interconnected in a strand from one another.
Alternatively, in a hot-compacting installation pre-reduced or completely directly reduced iron is also pressed in a roller press, but not into briquettes; instead, compaction is (first) performed in which an extrudate emerges from the press as an intermediate product that is referred to as “slug.”
This extrudate is then disaggregated, after which the material finally takes the form of a granulate that is generally processed further immediately, for example in another reduction process or in an immediately adjacent smelting furnace.
Since the material emerging from the presses has very high temperatures, the material, particularly if in briquettes, is first discharged to cooling conveyors on or in which the material is flowed around by a cooling medium, for example a liquid coolant (such as water) or a gaseous coolant.
To increase production capacity, several roller presses are generally used for briquetting or compacting.
Such an installation for hot-briquetting directly reduced iron of the type mentioned at the outset is known, for example, from WO 2000/055379. The known installation has four roller presses or four briquetting lines connected in parallel, for example, each of which is supplied from a storage bin with iron sponge in the form of fine particles via a respective “feedleg.” Between two respective briquetting lines or roller presses, a bucket conveyor and hence a transport device is provided for returning fine particles separated from the product by screens beneath the briquette presses. A respective cooling conveyor belt for cooling and delivering the briquettes is provided for two briquetting lines or roller presses. Alternatively, a space-saving arrangement of four briquetting lines or roller presses in a rectangular arrangement is described. Four feedlegs go from one storage bin to the individual briquetting lines. One common screen is provided for two respective converging briquetting lines. A line extends, in turn, from the each of the two screens to a single cooling conveyor belt that consequently receives all of the material.
An installation is known from DE 38 06 861 for transporting hot iron sponge from a direct-reduction system to the hot-briquetting system to the side of the shaft furnace. The hot-briquetting presses are located beneath a feed hopper for the material to be briquetted. They deliver the iron sponge as briquettes to screening, cooling and conveyor systems. EP 2 132 344 [U.S. Pat. No. 7,938,882] describes a method in which directly reduced iron can be delivered via supply conduits either to briquette presses or directly to a transport means. A material diverter is provided above the roller presses for this purpose. Finally, EP 2 641 981 describes an installation for manufacturing molten iron from directly reduced iron in which the directly reduced iron is compacted presses and then reduced to small pieces. The material emerging from the compacting presses or from disaggregators can either be conveyed via an upstream conveyor to a smelting furnace or stored on an interim basis in storage containers via a second conveyor. Diverters are beneath the disaggregators, so that the material can be optionally delivered to the smelting furnace on the first conveyor or to the storage container on the second conveyor. In such installations for hot-briquetting or hot-compacting directly reduced iron, the constant need exists to optimize capacity. Moreover, safety considerations are at the forefront when the installation is designed. For instance, during the processing of hot material from directly reduced iron, one must ensure that the briquettes are reliably transported away while simultaneously cooling, particularly including when system parts fail. This is where the invention comes in.